Electrical device



Oct. 12,1948. w. l. sTAAF 2,451,308

ELECTRICAL DEVICE Filed May 29, 1944 7 and/Mo( atentec Oct. 112, 9`4k8;

` UN'ITED STAT-Es PATENT OFFICE I ELECTRICALIDEVICE Werner I. Staaf, Rennerdale, P'a. Application May 29, 1944, serial No. 537,933

2 claims. (o1. 26o-4521) contact devices and contactbl'ades which may 1f become worn or spread, or may otherwise become unsatisfactory, the el'd of use of mercury switches as constructed at the present time is `relatively limited, due to the fact that the eiectof gravity -is principally relied upon for their operation. The more familiar types of mercury switches comprise glass tubes, mounted for tilting for turning movement, the arrangement being such that when theV tube is tilted or turned in one direction, the mercury gravitates to the lower lend of the t'ube'and closes a circuit, whereas 4when the tubeis tilted infthevreverse direction, the mercury 'ows to the opposite end and the circuit is broken'. Less coi'iiilon forms of mercury switches employ a reservoir and piston arrangement, wherein the movement of a plunger into the reservoir rraises the' height of a column of mercury to a point where the mercury contacts va circuit-closing elemerit` When vthe lplunger is withdrawn the column of mercury vdrops into circuit-interrupting position. 'The field in which 1 both types of 'switches' 'may be used is obviously limited, because ofthe effectl of gravity-and the elect of inertia. The' tilting devices' obviously may not be used in any vof vrriolo'ile equipment, because of i the' changes of inclination of such equipment, bouncing-sharp changes 'of direction, etc., and the Vsecond type of mercury switch mentioned is even less well adapted to such use.

The present invention provides a vmercury switch which is of simple and rugged construction, which is .positive in its operation, which is vprimarily not dependent upon gravity, and which eliminates delicate or elaborate pivoting or tilting suspension, and which may .be mounted in various Ways without resorting to elaborate specialized construction. It .provides a mercury switch which can be substituted in various places for movable contact blade switches now widely used, and it lmay be adapted for `operation by Y relays or other automatic actuating devices, as well as rfor operation'by'hand.

While'th'e 'structure of the invention is adapted `:for 'use 'as electrical make-and-break and/'or current conducting'devic'es' in general, it is par"- vti'cularly designed for electrical switches, kand herein I` shall so describe it, with the understan ing that within the terms of the appendedcfalms various devices, in which'a conductive fluid 'forms an essential current-carrying element, .are/included. In the accompanying drawings;

Figure `I isa view in transverse 'section' 'of 'a switch embodying the invention; y

'Figure is a VView'co'irlparable :with Figuejl indicating in dotted 'lines a Y'puslfi-liu't t'o'n `device that may be organized for operating the switch. Whereas in Figure I the V switch is shown in cir cuit-closing position', yin lFigure 'I 'the switch `is shown in, circuiteirteirupting 'positionj A Figure 1v is a view ijn'plan of a certainelement that -is embodied in the switchwstructure;

-Fig'ure Visa view interosfs section of a'modifred form-of the switch `ol the lrinvention;'and Y Figure is a'vie'w in :plan `of the modied structure of Figure v.

Referring tothe drawings, the switch herein 'illustrated consists ina container liornied of a block-like body 2 of electrical insulating or dielfc tric material that isshapedvk to provide an vannular well 3 Vfor 'a pool l4y of 'mercury or other electrical-conductive fluidi The body or blocks! -isv 'formed of porcelain, or lglass, or 'hard rubber or pressed fibre, or the like, which is not wetted bymeroury. At the center' of the' body 2 la conlic'alreces's 5 opens into the well 3, andthe botto 'of this recess is'formed by the laterally extended head-of a screw -6.' The sor'ew -6` provides one vof two/electrical contacts whichl are accessible tothe mercury within the sm'tch structure.

Thebody@4 of the switch-is encased-in a--nusi'ns 'formed of a Ad-'slil "1 y0f hard rubber orother suit- :able insulating material, a circumferential' metal sheath' 8, and'- la fieblemetafl' diaphragm 9, the -me'tal diaphragm-being 'united (as by welding)v 'in l.a 7lilfiuid-tight joint 'Sato theiadjacent edge of the sheath 8",1 and the' 'opposite l edge ofi the sheath JB 'being peripherally clinched, as at to,l up'o' the edge' of the disk 1. 'A complete 'enclosure'o Y the s'witchstructurefis thus provided, Asv'v lires"- f'ently appear, :the metal body of the y'dialilifragrn 9 comprises'thelothfer' of thetwo electricaleontact's kwhich are accessible- 'to the` mercury within the switch. Y I

'As exemplary of means vfor' rigidlys'e'cuii'ng-th'e in'two lugs for ears '-Ta, per'fcfl'r'ated for the-use of "screws for bolts inobvios way.

Il'The threaded stem of the screw 6 is extended outward through the insulating disk 1, and an electrical connector I is secured thereto by and between two nuts Illa, while a gasket 6a of insulating material is positioned between the head of the screw and the disk 1 to provide a tight assembly of the parts. The outer end of the connector I0 is equipped with a conventional clamp' ing screw I4 to provide one terminal of the switch for the connection of a conductor A of an electrical circuit.

A metal band I5 is clamped in electrical union upon the metal casing of the switch by means of a screw I6, and this screw serves notonly to secure the band, but additionally to provide the other terminal to which an electrical conductor B A may be attached. Thus, it will be perceived that the switch may be connected in an electrical circuit A, B. Since the screw 6 and the metal diaphragm 9 severally stand in electrical -communication with the switch terminals I4- and I6, it,.will be understood that the body of mercury within the switch -isVV adapted to close a circuit through the conductors connected to the switch, asindicated in Figure 1. i

accordance with the` invention, I provide partic'ilarly effective means within the switch structure positively to move themercury between a position in which the circuit A, B is closed and a position in which the circuit is open. Such means advantageously consist in a device which physically displaces so much ofthe mercury as is necessary to achieve such eiect. In this case, the device comprises a member VI1 formed of insulating material and mounted for movement fromthe circuit-closing position shown in Figure 1 ,(in which-the bodyfof mercury electrically unites .the screw 6 withfthe metal casing 8, 9 and closes the circuit) to the circuit-interrupting position shown in Figure 3 (in which the member -I1-,displaces `the mercury tothe extent necessary tolrm a barrier of insulation in the path 0f electrical communication between the switch terminals). The member I1 is here lshown as a block of porcelain, or other insulating material,

y,whichhlike the body VZig not wetted by the mer-` cury. The means for supporting such block for 'movement between said alternate positionsV comprisr-rthe flexible diaphragmV 9 of thev switch casing.- Y 'y f Moreparticularlm the block I1 is attached to a metal ldisk I8 formed with a castellated periphery,jthe attachment being effected by rclinching the projecting portions of the castellated edge of the disk upon the beveled rim of the block. The metal disk I8 is secured tothe center of the diaphragm 9 by means of a 'stud 20, .and the diaphragm is adapted under stress ape plied to the stud to be ilexed from the position in which itis shownin Figure 1 v'to the position shownin Figure `3.y The movement of the dia- -phragm between suchpositions is a snap-action `movement which shifts the mercury-displacing blockgIT between its alternate circuit-controlling positions, and the design and elasticity ofV the diaphragm are such that the diaphragm `is adapted to maintaintheblock I1 in either of said positions into which it is sprung.

{.It ,will be understood that, whenV the block I1 moves into circuit-interrupting position, it disposition on said annular portion 2a. By virtue ofthe iact that the body Zand the block I`1 are formed of material that is not wetted by the mercury, there is no tendency for any of the mercury to remain between or adhere to the meeting surfaces of the block and the container body. Accordingly, while the recess or well 5 may contain mercury when the block I1 is seated'over the mouth of the well, there is absolute electric isolation of the head of screw 6 from the metal casing of the switch; that is, the terminals of the switch are isolated, with the circuit A, B open or interrupted.

In order that the block I1 shall not hamper the deflection of the diaphragm, a spacer 2| is positioned between the block and the diaphragm. The stud 20 is shaped externally of the diaphragm in the form of a grooved head 20a, and

this head formsabutton that may be pushed or Y tional wall switch (not shown) the head ZIlaof l the stud aords means for connecting the mer.-4 cury-dlsplacing block or plunger I1 to the switchoperating mechanism ofY the wall switch.V In Figure 3, the cover plater22 and toggle 23 of a push-button wall switch are indicated in dotted lines, and the manner in which the toggle arm may be engaged in the groove of the head 20av to provide for push-buttonpoperationof the switch will be manifest to those skilled in the art. Y

It will be perceived upon consideration of the drawings that the switch structure will be operafl tive in any position in which it may be mounted on a support, save a horizontal position in which the stud head 20a is directed downward, for with the switch in that position the mercury will lie in' a pool upon the inner face ofthe diaphragm and will not make contact with the head of the screw .Ii-to complete the circuit in which the switchis connected. But, it will be understood that this circumstance imposes no serious impediment upon the utility of the switch under normal conditions of service.` A.

Figures 5 and 6 illustrate one of the many permissible modified forms of the structure of the invention. Whereas in vthe device of Figures 1 to 4 the mercury-displacing block I1 comprises Ya plunger that is movable in a directionv normal to the mouth of the recess 5 and the head of the contact screwG exposed therein, in the modified structure the plunger block I1e is adaptedl to move transversely of the mouth of the recess 5c, the container body 2c being` appropriately modiiied in form to provide an elongate seat 2d` surrounding the recess 5c and upon which the block I1c may slide.` The metal casing 8c is modified in.

Since the casing 8c is formed as a castingthe ,insulated disk 1c vthat forms the casing wall portion through which the contact screw 6c extends is secured in place by means of an independently formed clamping ring 8d drawn tight by meansv of screws 8e threaded into the body of the casting 8c. One terminal, |40, of the switch is` connected to the contact screw Ec as in `the Ystructure first described, andthe other terminal,

I6c, is attached to the metal casing 8c, 8d with which the pool llc of mercury is in contact.

The means for shifting the mercury-displacing plunger between its alternate circuit-controlling positions comprise a plunger rod 24 that extends outward from the metal casing through a stuing box whereby it may be equipped with, or connected to, suitable means for eiecting the switch-operating reciprooation of the rod, as desired. The attachment of the plunger rod to the block l'lc is formed by a stud 20c rigid with the disk 80 that is united to the block, and this stud fits in an orice provided in the end of the plunger rod, which is flattened at its inner end, as shown, to accommodate an orice of the diameter of the stud. A leaf spring 26, clamped at one end between the assembled body 2c and casing Bc, bears upon the otherwise free end of the stud, and serves to hold the mercury-displacing block in snug contact with the seat 2d upon which it slides. With the parts in the positions in which they are shown in Figure 5, the block I1c manie festly electrically isolates the switch terminals Mc and |60, whereby the circuit in which the switch is included stands open. Alternately, upon the outward movement of the plunger rod 24, the block I'lc is moved tothe right into a position in which the pool of mercury electrically unites the contact screw 6c with the metal casing of the switch, and thereby electrically unites the switch terminals and closes the circuit in which the switch is connected. Thus, the reciprocation of the plunger rod is adapted to shift the mercurydisplacing element llc between its alternate positions to open and close said electrical circuit.

It will be seen that both of the structures described function on the same principles of operation, and it will be understood that many variations in structure lie within the eld of invention covered in the appended claims.

I claim as my invention:

1. A positive displacement mercury switch comprising a block of dielectric material and a housing member comprised of electrical conducting material assembledwith the block to form an enclosed Well, a recess formed in said block of dielectric material to open into said well, a body of mercury in said well and recess, said block including a portion forming a seat that encompasses said recess, an electric contact element exposed in said recess to said body of mercury and extending outward from the block to form a circuit terminal, and a plunger of dielectric ma- Y terial movable in said well into and from position on said seat and adapted when positioned on said seat to provide an electric barrier 4between said contact and the mercury in said well in contact with the electrical conducting material of said housing.

2. The structure of the preceding claim, said housing member comprising a flexible diaphragm to which said plunger is connected for movement therewith.

WERNER I.. STAAF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

